import math
x1, y1, x2, y2 = map(float, input().split())
x = x2 - x1
y = y2 - y1

result = x**2 + y**2
print(math.sqrt(result)) import math math x1, y1, x2, y2 = map(float, input().split()) x1 map(float, input().split()) map float input().split() ().split () input split y1 x2 y2 x = x2 - x1 x x2 - x1 x2 x1 y = y2 - y1 y y2 - y1 y2 y1 result = x**2 + y**2 result x**2 + y**2 x**2 x 2 y**2 y 2 print(math.sqrt(result)) print math.sqrt(result) math.sqrt math sqrt result x2, y2 = map(float, input().split()) map(float, input().split()) x2 x = x2 - x1 x2 - x1 x y2 = map(float, input().split()) map(float, input().split()) y2 y = y2 - y1 y2 - y1 y result = x**2 + y**2 x**2 + y**2 result x1, y1, x2, y2 = map(float, input().split()) map(float, input().split()) x1 y1, x2, y2 = map(float, input().split()) map(float, input().split()) y1
import math
x1, y1, x2, y2 = map(float, input().split())
x = x2 - x1
y = y2 - y1

result = x**2 + y**2
print(math.sqrt(result))